Fuel pump installation in 240Z tank

[DJACEY]

I want to install the standard rb25 fuel pump into a 240Z gas tank. Does anyone have any pics and information on the hole diameter required, best fixing method, standard/modified parts needed etc. Also, any information on installing the fuel filter(s). Can the standard 240Z fuel pipe diameters be used down the tunnel or do I need to uprate them to cope with the flows ? Thanks.

[kcelectronics]

HI

Why do you want to install in the tank? is it because you already have an in-tank pump assembly?

 

I have just gone through the whole process of EFIpump/fuel tank issue, I had an internal and an external pump on hand, and this is my story.

 

History

I have had an EFI 2.8 fitted for 10 years and was running a "4lt Swirl Pot" bolted to the side of the original fuel pump bracket, this had 4 fittings, 1 was supplied by a low pressure pump (like the std fuel pump), this keeps the "pot full at all times, the 2nd fitting at the top allowed the fuel pump to fill the pot and allow the extra fuel back into the tank, there is a good reason to do this, as continually pumping fresh fuel into the "Pot" it helps to "cool" the fuel in the" swirl pot" (I will explain later why I had changed this set up), and don't worry about the "flow rate" of the low pressure pump, it only has to replace the fuel used by the engine, so capacity is really not so important for a "Street Car", this is because there is more than enough fuel in the Swirl Pot for full a throttle run, after which the swirl pot has time to be refilled again. The other 2 fittings supply the High Pressure (35-60psi) EFI pump from a fitting on the bottom of the pot, the other is the return from the engine bay.

 

So to put it simply, the low pressure fills the swirl pot, and the high pressure runs the engine simple.

 

 

 

 

I will now explain why I changed this old set-up? as it has worked very well but with 1 major problem!! HEAT pure and simple, 99.5% of the time this system was perfect, it was easy to set up and maintain, but on very hot days out on the highway the heat in the engine bay would heat the fuel being returned to the swirl pot, so after 20~30 minutes the fuel was so hot it would vaporise, guess what NO liquid fuel =NO GO? and the small amount of fresh fuel added from from the tank would not help. I did try to fix this set up by returning the "Hot" fuel back to the main tank, but the low pressure pump couldn't keep up with the EFI Pump.

 

This leads me to the latest set up!

I thought about what was needed and it isn't rocket science, all that is required is a constant supply of high pressure fuel Simple.

 

The problems we face with our older Z's is the tank design, there isn't a Baffle or "swirl pot' inside our tanks, (unless you fit a 280z tank?) but over here in Australia and I think in the UK we didn't get the EFI in the early Z's so this option is out.

 

So to fix the problem we have 2 choices (yes I finally go to the answer to the question) Internal or external pump?

 

Both are going to be time consuming and possibly very dangerous!!!! (See Bottom of Page)

 

1. Internal pump, requires the tank to be opened up to allow the fitting of a baffle/swirl pot, this keeps the fuel around the pickup for the pump so there are no interruptions to the fuel delivery (EFI motors don't like interrupted fuel supply's), caused by the fuel sloshing around when Accelerating braking or going around corners! (especially with low fuel in the tank) this can be minimized by keeping the tank more 1/3 full, but as the tank would need to be opened up to fit the pump anyway, why not as Mike Holmes says, "Do It Once and Do It Right"? once the baffle/swirl pot is in place, then fit the internal pump assembly I was intending to remove the part of the donor tank and welding it into place (Warning see below) the pump I was going to use had the fuel gauge sender as part of the assembly, and I was intending to fit it where the original one was located.

 

This was getting a bit complicated SO.

 

2. External Pump Pull tank cut hole in bottom, fit sump (literally as it turns out) run fitting for fuel to EFI Pump and refit!!

 

So after much thought I went for the external pump.

 

 

Warning welding fuel tanks can be very dangerous Period!!!!:nono:

i am not going to tell you how to do this!! It is up to you to decide if you are capable OK.

All I will say is I did it by washing out the tank several times with soapy water, leaving out in the hot sun for a few days, than running a flexible pipe from my exhaust (the car's not mine! LOL) this fill's the tank with Carbon monoxide? which should remove any explosive gas (again petrol not mine LOL) that may be present.

 

I Accept No Responsibility For any situations you may get yourself into!!!

 

 

 

If you want the story of the tank mod's for the external pump just ask OK

[Canadianz]

Just a tip, instead of using exhaust from your car, I would recommend using pure C02. The easiest way is get one of the 20 ounce cylinders that are used for paintball and vent it into the gas tank. CO2 will not burn and has the benefit of being slightly visible as a fog so you can see any pinhole leaks in your tank at the same time. Another alternative would be shielding gas from a mig welder, again non-flammable although probably more expensive. Welding gas tanks is safe is done correctly but a deathwish otherwise.

[jerryb]

HAHAHA...I left mine in the sun for a week and then purged the tank with my compressor for a couple of hours AND then directed a hot stripper gun onto the opening for 4 hours....slowly on cold first.

 

Never though of the C02....I probably would have done that as well!

[DJACEY]

Thanks kcelectronics - great reply ! You cant beat experience and it prevents others from making the same mistakes and saves them time and money.

 

Could you please give me the details of the tank mod's for the external pump. Sounds like the best and easiest option.

 

Dave

[Careless]

I have a question about your experience, kcelectronics.

 

HI

and don't worry about the "flow rate" of the low pressure pump, it only has to replace the fuel used by the engine, so capacity is really not so important for a "Street Car", this is because there is more than enough fuel in the Swirl Pot for full a throttle run, after which the swirl pot has time to be refilled again.

 

 

I did try to fix this set up by returning the "Hot" fuel back to the main tank, but the low pressure pump couldn't keep up with the EFI Pump.

 

Why wouldn't you just get another higher volume pump?

 

Some math here (please tell me if I'm wrong):

 

Walbro pumps (lets use this as the standard for our equations) pump at 255 Liters per hour.

 

Lets convert that to gallons using two decimal places

 

255 / 3.78 = 67.36

 

Lets convert that to gallons per minute

 

67.36 / 60 = 1.12

 

So we have a final volume of 1.12 Gallons Per Minute or 4.2 Litres per hour

 

Mr. Gasket Company, as an example...sells a pump called the Universal Micro Electric Fuel Pump.

This pump is compatible with all fuels and additives, and is good for fuel transfer, as it has 4 to 7 PSI, and is rated at 35 gallons per hour, as well as a 2 to 3.5 PSI model, rated at 42 gallons per hour.

 

These are MINI PUMPS. I'm sure there are some full size units that can flow upto 75 GPH.

 

no?

[kcelectronics]

I have a question about your experience, kcelectronics.

 

Why wouldn't you just get another higher volume pump?

 

HI Careless,

yes the higher flow low pressure "lift" pump would have worked, in fact the car that the RB30 comes from the GM Holden VL Commodore has a lift pump in the tank (which has a "baffle/Swirl pot") to feed the external pressure pump, I have one of these pumps and intended to use it, but as it was an in-tank type I might as well fit an in-tank H/P pump. (the reasons I didn't go this route are outlined above)

Also the reason that the donor car has this arrangement is that it was designed for carburetters with engine mounted fuel pump, so when the Nissan EFI engine was fitted the the same fuel tank was used with the Low/High pressure set up.

Another reason i didn't go this route was because if the in-tank lift pump fails, the obvious happens, No fuel = No Go, and as I believe in the K.I.S.S (keep it simple stupid) principle I wanted to eliminate the "Extra Pump".

 

I will describe the tank mod I now use ASAP (I need to locate the few pictures I saved on my crowded PC)

[Careless]

HI Careless,

yes the higher flow low pressure "lift" pump would have worked, in fact the car that the RB30 comes from the GM Holden VL Commodore has a lift pump in the tank (which has a "baffle/Swirl pot") to feed the external pressure pump, I have one of these pumps and intended to use it, but as it was an in-tank type I might as well fit an in-tank H/P pump. (the reasons I didn't go this route are outlined above)

Also the reason that the donor car has this arrangement is that it was designed for carburetters with engine mounted fuel pump, so when the Nissan EFI engine was fitted the the same fuel tank was used with the Low/High pressure set up.

Another reason i didn't go this route was because if the in-tank lift pump fails, the obvious happens, No fuel = No Go, and as I believe in the K.I.S.S (keep it simple stupid) principle I wanted to eliminate the "Extra Pump".

 

I will describe the tank mod I now use ASAP (I need to locate the few pictures I saved on my crowded PC)

 

so you had this setup running on an RB30, then? How much fuel pressure and how much flow is required for your power level? I have a 500 ml surge tank that I might use, not sure if it's sufficient enough. I may make a 1.5 litre one using a previa receiver dryer.